Method and device for decontamination of ground

ABSTRACT

A method and a device for decontaminating soil on the spot from harmful substances. In the soil one or several horizontally drilled holes ( 10 ) are arranged debouching into the ground surface. In the hole a chord ( 16 ) is inserted in form of a hose or a number of interconnected sockets, in which reactive sorbents are stored. The chord ( 16 ) remains in the ground during a sufficiently long period for achieving a desired decontamination of the soil.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for decontaminating soil onthe spot from harmful substances. The invention also relates to a deviceto accomplish the method.

2. Description of the Related Art

There are today over the world existing large areas with contaminationedsoil. Grounds being contaminated by harmful substances, such as heavymetals, but also PCB, chlorinated hydrocarbons, etc.

Thus, it has become a large field of research to develop technologies toremove poisons from the soil and a number of different methods has beenproposed. A method has i.a. been proposed, by which the poisoned soil isremoved and transported to decontamination facility, in which the soilis cleaned and thereafter restored to the ground area, where the removaltook place. Such a method and the matching device become verycomplicated and thereby expensive to accomplish, the facility becomingi.a. automatically mobile to be usable in ground areas to be cleaned, orthe soil has to be transported to a stationary facility far from theground area. Also chemical methods have been developed to cleancontaminated grounds, microemulsions then being pressed into the groundto wash the decontaminations away from it. Even this last mentionedmethod becomes complicated due to the aggregates pressing down themicroemulsions and pumping these again out of the contaminated ground.

SUMMARY OF THE INVENTION

The main object of the present invention is to present a method forcleaning grounds, in which the drawbacks of already known methods mightbe avoided and which in a simple and inexpensive way provides a cleaningof contaminated grounds.

Another object of the invention is to provide a device, by means ofwhich contaminated grounds can be cleaned in a simple and inexpensiveway.

These and other objects and advantages of the invention are achieved byproviding it with the characteristics specified in the claims to follow.In accordance with the invention at least one generally horizontal borehole is created in the ground which communicates with an opening to thesurface of the soil and a chord is inserted within the bore which chordincludes reactive sorbents. The chord is retained in the ground for aperiod of time to allow the sorbents to provide for desireddecontamination of the adjacent soil.

The invention will be described herein below more in detail inconnection with the drawing, providing an embodiment of a device foraccomplishing the method according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross section of a ground area to be cleaned

FIG. 2 shows a plane view along the line II—II in FIG. 1.

FIG. 3 shows a section along the line III—III in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As shown in FIG. 1 a horizontal hole 10 is drilled in the ground to becleaned, this being achieved by means of a technology known in the art,a drill being inserted at an angle into the ground at an entrance hole12 and being drilled horizontally along a distance appropriate for thecleaning and with respect to the equipment adapted to about 100 to 200meters, before the drill is lifted out of the ground at an exit hole 14.Several such holes 10 are drilled parallel with each other in accordancewith FIG. 2 to cover the ground area to be decontaminated in the otherdirection. The distance between the holes 10 in this other directionmight be of the order of 1 of 3 meters, e.g. 2 meters, depending on thecircumstances in the contaminated ground to be cleaned.

According to the invention a chord 16 of an appropriate material, suchas a plastic material, is inserted in the drilled holes, the chord 16connecting a multitude of, at appropriate intermediate intervals, spacedsockets 18 for a sorbent. The sockets 19 consist of a material lettingliquid pass into and out of the socket, such as a net material withmeshes of a magnitude to retain sorbent particles in the socket 18. Thedistance between the sockets 18 on the chord 16 is a function of thetype of sorbent and the conditions of the poisoned soil to be cleaned,the distance being such that the sorbent in two neighbouring sockets 18are operating on the itermediate ground surface both in the longitudinaland the transverse direction. If it is necessary to reinforce the hole10 and to facilitate the insertion of the chord 16, the hole might belined with a slotted or perforated hose or liner 20 having openings 22,as shown in FIG. 3.

Instead of the embodiments here shown in might be envisaged that thechord 16 itself consists of a hose with fine meshes containing thesorbent, eventually with compressed portions in the hose in appropriatespaces to keep the sorbent equally distributed in the hose. In this casethe socket 18 might be abolished.

Zeolites with a chrystalline structure might be used as a sorbentprovided in the sockets 18 providing a large absorption capacity andthus absorbing large quantities of different kinds of materials, such asheavy metals and other harmful substances. The absorption is achieved inthat the soil is moist and in most cases the moisture of the soil itselfwill be sufficient for the desired effect, but water might be added ifthis is desirable so that the ground is moistened at the drilled holes.When the chords of the sorbent sockets have been lying under the groundfor a sufficiently long period to achieve the desired cleaning ordecontamination of the soil, the chord is retracted out of the hole andthe employed sorbent can be regenerated for a new application for adecontamination of further areas.

From the description above it is evident that a very simple andinexpensive method has been provided to decontaminate large areas ofpoisoned soils on site without and handling of the soil itself beingnecessary.

Obviously, the embodiment shown above represents merely an example ofthe implementation of the invention and changes might be made withoutleaving the scope of the invention. Thus, the sockets 18 can haveanother form than that already shown, e.g. having a spherical orlongitudinal shape arranged with larger or smaller intermediate spacesor consisting, as stated above, of a single hose, eventually compressedin equal intermediate spaces.

The sorbent might also be another one than zeolite, depending on thetype of contamination to bc removed from the ground.

What is claimed is:
 1. A method of decontaminating soil on site from atleast one harmful substance including, drilling at least one generallyhorizontal bore hole in the soil which communicates with at least oneaccess hole which extends to a surface of the soil, inserting a chordmember containing at least one reactive sorbent of a type having acapacity to remove at least one harmful substance from the soil, andretaining the chord member within the at least bore hole for a period oftime sufficient to achieve a desired decontamination of the at least oneharmful substance from the soil.
 2. The method of claim 1 includingforming the chord member in a form of a number of interlinked and spacedsockets in which the at least one sorbent is retained.
 3. The method ofclaim 2 including forming the sockets of a net-like material in whichthe at least one sorbent is retained.
 4. The method of claim 1 includingforming the chord member in a hose structure with a net-like material inwhich the at least one sorbent is retained.
 5. The method of claim 1including inserting a liner having openings therethrough within the atleast one bore hole and thereafter inserting the chord member within theliner.
 6. The method of claim 1 in which the at least one sorbentincludes a zeolite.
 7. The method of claim 1 including moistening thesoil in an area of the at least one bore hole.
 8. The method of claim 1including removing the chord member from the at least one bore holeafter the desired decontamination is achieved and regenerating the atleast one reactive sorbent.
 9. A device for decontaminating soil on siteby removing at least one harmful substance from the soil, the devicecomprising a chord member in which at least one sorbent material of atype having a capacity to remove the at least one harmful substance fromthe soil is contained, said chord member being of a configuration so asto be adaptable to be received within an elongated bore hole provided inthe soil.
 10. The device of claim 9 in which said chord member includesa plurality of spaced sockets, said at least one reactive sorbent beingcontained within said sockets.
 11. The device of claim 10 in which saidsockets are constructed of a net-like material having a mesh sizesmaller than a particle size of the sorbent.
 12. The device of claim 9in which said chord member is in a form of a hose.
 13. The device ofclaim 12 in which said hose is constructed of a net-like material havinga mesh size smaller than a particle size of the sorbent.
 14. The deviceof claim 9 including a liner member of a size to receive said chordmember therein, said liner member including a plurality of openings.